1. Field of the Invention
The present invention relates to a closed type heating apparatus which is advantgeously used on a floor and wall of a room and on a bed.
2. Description of the Related Art
Heretofore, there has been proposed a heating apparatus comprising duets or pipes arranged inside the floors and walls of rooms. However, such a heating apparatus is liable to be large and requires high construction and maintenance costs. There has been also proposed a simple heating apparatus such as electrical heating carpets and mats which may be simply arranged on the floor. However, these heating apparatus have a low heating efficiency so low that their maintenance costs would be high. Moreover, these apparatuses might be adversely affected by water or moisture, and the safety of the apparatus might be diminished after a long time.
There have been further developed heating apparatuses which can heat restricted areas. For instance, warming pans and hot water bottles have been used for heating bedclothes. Moreover, blankets and bed sheets having electric heaters installed therein have been also proposed. The warming pans and hot water bottles have drawbacks in that their heating function is restricted locally and further in that a user might get a low temperature burn due to hot water leaking from the bottle. Further, the electrically heated carpet and bed sheet can heat rather large areas, but the temperature distribution is not optimum. The user can feel comfortable when his or her feet are kept warm and his or her head is kept cold. Moreover, the weight and hardness of the electric heater might make the user uncomfortable. Further, an electrically heated carpet and bed sheets can not be easily washed. If they might produce a foul smell. In addition to the above mentioned drawbacks, the electrically heated carpet and bed sheets have a drawback in that safety can not be attained easily due to the leakage of electricity.